Drainage systems using precast and molded sections are known as exemplified by U.S. Pat. No. 4,940,359 and U.S. Pat. No. 5,213,438.
U.S. Pat. No. 4,940,359 discloses an elongate safety conduit or trench for receiving chemical liquids, having first and second preassembled conduit elements, the first located and retained within the second.
U.S. Pat. No. 5,213,438 discloses an elongate safety conduit or trench for receiving chemical liquids, having inner and outer preassembled conduit elements. The outer element is greater in width and depth than the inner element to accommodate the longitudinal slope of the inner element while providing a space beneath the inner element to collect any fluid leakage.